In 1969, Philip Roth's most famous character, the sex-obsessed Alexander Portnoy confessed to his analyst: "What I'm saying, Doctor, is that I don't seem to stick my dick up these girls, as much as I stick it up their backgrounds – as though through fucking I will discover America." That was 40 years ago, but the reverberations are still being felt. Portnoy's Complaint, which the New Yorker greeted as "one of the dirtiest books ever published", helped Roth shake off any lingering respectability he had earned from his early novels. "Enough being a nice Jewish boy, publicly pleasing my parents while privately pulling my putz!" cried Portnoy from his analyst's couch. As he did so, Roth was denounced by leading Jewish figures, while critics went wild and the novel became an instant bestseller. The respectable boy from Newark, New Jersey had embarked on his lifelong work refining what has been called his art of immaturity.

Roth used the brilliant conceit of Portnoy's Complaint – a monologue delivered by a neurotic man to his psychoanalyst – as a way of exposing the guilt-ridden mess the Jewish male found himself in during the 1960s. While sexual liberation was blooming all around them, nice Jewish boys were trying to reconcile their insurgent libidos with their strict family backgrounds. Fizzing with exclamation marks and capital letters, the pages of Portnoy's Complaint caused such uproar because they were the first to show "a Jew going wild in public", which according to Roth was "the last thing in the world a Jew was supposed to do".

And Portnoy certainly goes wild. His revelations are delivered with feverish abandon. From his early teenage years – where his obsession with masturbation sees him making love to a raw liver his mother later serves for dinner – he chronicles his transformation into a "cunt crazy" adult male, spending his days "chasing it, sniffing it, lapping it, shtupping it, but above all, thinking about it". Portnoy is bent on grounding Jewishness in something human, dirty and real. As he famously screams at his therapist: "LET'S PUT THE ID BACK IN YID!"

So how does it stand up in 2009 – now that explicit novels such as Charlotte Roche's Wetlands and Chuck Palahniuk's Snuff are as likely to provoke boredom as outrage? Does it retain its power? I'd argue that it does – for two reasons. First, the book shows Roth striking the wellspring that has flowed through his writing ever since: the connection between sex and mortality. As Portnoy explains in a rare moment of non-obscenity, his flaming libido represents "the desire continually burning within for the new, the wild, the unthought-of and, if you can imagine such a thing, the undreamt-of". As with Roth's recent novels, in which elderly protagonists rage against their dwindling virility (David Kepesh in The Dying Animal; Nathan Zuckerman in Exit Ghost), Portnoy's Complaint asserts that to be sexual is to be fully alive – while to have that denied is a form of living death.

Second, the novel transcends its own vulgarity – placing it beyond easy dismissals as mere literary porn – by using sex to explore pretty much everything else: history, culture, identity, religion, politics. High on the euphoria of confession, Portnoy divulges not simply his fondness for "whacking off" – considerable though that is – but also his desire to escape his Jewish history by heading to the sexual frontier in search of a new identity – "As though my manifest destiny is to seduce a girl from each of the forty-eight states", as he puts it. And this works both ways for characters in the novel. The filthy antics Portnoy gets up to with his all-American girlfriend from West Virginia are their mutual doomed attempts to escape everything they find loathsome about their cultural inheritance.

So despite reaching 40, that milestone of respectability, Portnoy's Complaint is still a masterclass in how to get beneath the skin of sexuality. Has any other novel managed it quite so well?